There are 2 basic types of piston crown coatings,
first is the older style that is either light grey a silver color, or in some cases black.
those coatings tended to break down at just over 1000F
This coating is very similar to what is used to prevent rust on coated headers
The newer heat barrier coatings are frequently gold in color; they can handle higher temperatures in the 1600F or slightly more range, such as nitrous or turbo engines tend to have.
the coatings tend to block the transfer of much of the combustion chamber heat to the lower piston reducing the tendency to get into detonation on the sharper edges of valve pockets, or edges of pistons The coatings tend to keep the to heat locked into the combustion chamber where it promotes a more rapid flame front, reducing the need for longer ignition advance curves.that reduction in heat tends to reduce the reduction in strength that high engine temperatures can have on aluminum alloys, that tends to increase piston life and durability.
you can run a little tighter than before since your pistons will stay cooler and not expand as much, that means less rocking when cold and a tighter bore fit for better oil control and better ring seal.
most shops carefully tape the ring grooves then chemically etch the piston decks to gain a better mechanical grip to the pistons upper surface for the thermal barrier coating, some shops use a steel shot process, to gain a micro rough surface finish before the coating applied.
while the price to coat a piston can easily come to 50% of the cost of the less expensive pistons if it prevents a catastrophic engine failure its well worth the expense
while thermal coating benefit's either the piston or the combustion chamber ,yet it tends to do more, if on the piston,too increase piston durability through reducing heat that tends to reduce aluminum strength in the piston deck or top surface area,
and coating the combustion chamber probably results in a bit more efficient burn in the combustion chamber , as more heat energy is at least for a few fractions of a second retained in the expanding combustion gases,and marginally less heat transfer to the heads, valves and coolant can occur, so in theory you get a bit longer pressure pulse above the piston with either option, but with the combustion chamber coating I think you'll benefit the power/tq curve just marginally more, but that piston durability factors probably more critical to longer term engine durability
links with more detailed info,
http://www.thermaltechcoatings.com/services.htm
http://www.hightechcoatings.com
viewtopic.php?f=53&t=4516
http://www.circletrack.com/enginetech/c ... index.html
http://www.circletrack.com/enginetech/c ... tions.html
http://www.swaintech.com/store.asp?pid=10971
http://www.swaintech.com/store.asp?pid=10539
http://www.performancecoatings.com/enginecoatings.html
http://www.powdercoatingmn.com/power.html
http://www.calicocoatings.com/
engine Coatings - Coated Paths to Power
Race Engine Coatings
These lifters feature a special...
Race Engine Coatings
These lifters feature a special DLC coating. DLC stands for diamond like carbon which creates a super low friction surface that is both harder and more scratch resistant than conventional surfaces. Courtesy of Comp Cams
Dry Film Lubricants - These are the friction reducers, sometimes called "solid film lubricants." Far surpassing the benefits of bygone molybdenum disulfide suspended in lubrication oil, dry film lubricants are highly effective in reducing friction, heat, and surface galling. Since the lubricity portions of these materials are what provide the benefits, it's important that a good binder be utilized to keep the lubricants in place. Aside from gains made in friction reduction (particularly friction horsepower), the companion benefit is in heat reduction at the working surfaces.
Chemical or Corrosion Resistant Coatings - Materials in this category serve two fundamental purposes; (1) extended product durability or use life and (2) maintenance of appearance. We'll touch on specific areas where these coatings are of value a bit later.
In the same order they were previously presented, let's examine some specific uses for the coatings categories discussed.
Thermal Barriers - Here, the obvious areas are the combustion space and exhaust gas path. As mentioned earlier, my first and disappointing experience coating piston crowns showed power gains but damaged parts. Fortunately, with today's coatings technology, such problems are passe. So as you might expect, coating piston tops (and bottoms), combustion chambers (in certain applications), the faces of intake and exhaust valves, and complete header systems with these type of heat-retention coatings can be of particular benefit. Keep in mind that power equates with heat in a controlled environment. Therefore, combustion heat lost to cooling systems, combustion surfaces (all of them), and along the exhaust path can combine to reduce net power. Your best bet is to either consult with your choice of parts manufacturer already providing coated parts, or identify a good supplier of coatings materials if you elect to do the job yourself. And don't rule out the latter. Given the current state of some "kits" that are user-friendly to the engine builder, you can also get good results by these methods.
Race Engine Coatings
This camshaft has a new pro...
Race Engine Coatings
This camshaft has a new pro plasma nitriding process that enhances the performance all around. Courtesy of Comp Cams
Thermal Dispersants - Wherever you find that heat buildup is a concern, these are the materials to consider. Such components as brake parts, oil pans, radiators and intake manifolds all can fall into the need for rapid heat transfer or control. In areas where continual and/or repeated temperature spikes occur and you need to move heat more quickly away from these locations, consider these coatings to be of value.
Dry Film Lubricants - Remember, simply stated, friction horsepower is the arithmetic difference between indicated horsepower and brake horsepower. Therefore, the lower the friction horsepower, the higher the brake horsepower. So, by the use of dry film lubricants in areas that will net a reduction in friction horsepower, you can expect net power gained at the flywheel. Also expect a reduction in both surface and component operating temperatures. Applicable parts include valve springs, engine bearings, camshafts, and piston skirts and pins. Once again, you have the options of either selecting precoated parts or consulting with one of the coatings providers. Should you decide on the first option, it's wise to spend time talking with the manufacturer about the material (and its benefits) on any precoated component.
In this section, it may be helpful to discuss the benefits from coating certain major engine components. We'll include a few reasons and their basis, too. Our intention here is to stimulate some thoughts to the extent you'll begin to identify other parts and how they may benefit from coatings that address specific problems.
Valve Springs - Smokey once contended that valve springs raise the operating temperature of engine oil more than combustion heat. He'd already discovered that with his own version of today's "Spintron" spin fixture. Included in that discussion was his belief, other than valve float, that heat foreshortens spring life more than anything else.
Essentially, there are two sources of heat in a valve spring. One is derived from the friction of a spring moving against other surfaces (inner springs, harmonic dampers, etc.) and the other from the "flexing" or "working" of spring material during normal operation. Studies have shown that a valve spring is never motionless, even when the valve is seated. Residual energy and harmonics traverse an otherwise "static" spring, while the valve is on its seat. Consequently, heat within spring material is continually being generated. Heat is a principle source of damage to springs and, since valve springs are cooled by oil, you can expect other parts of the engine to correspondingly experience increased oil temperature.
most shops that, customize pistons round off any sharp edges, cut the piston valve clearance, notches and polish the pistons to reduce heat absorption and reduce detonation, and some coat the pistons coat the top surface with a thermal barrier coating, some match it with a combustion chamber thermal barrier coating , the coating your showing is designed to hold oil and reduce friction
you might want to read thru these threads and their sub links
viewtopic.php?f=53&t=2610&p=6737&hilit=coating+thermal#p6737
viewtopic.php?f=50&t=501&p=11829&hilit=clay+clearance#p11829
viewtopic.php?f=53&t=4472&p=11747&hilit=domes#p11747
THERMAL BARRIER DESIGNED TO REDUCE HEAT TRANSFER< AND INCREASE POWER
oil shedding coating on the under surface of the piston designed to speed heat transfer and reduce oil retention to reduce weight
outer skirt coating designed to increase wear resistance and retain oil film
first is the older style that is either light grey a silver color, or in some cases black.
those coatings tended to break down at just over 1000F
This coating is very similar to what is used to prevent rust on coated headers
The newer heat barrier coatings are frequently gold in color; they can handle higher temperatures in the 1600F or slightly more range, such as nitrous or turbo engines tend to have.
the coatings tend to block the transfer of much of the combustion chamber heat to the lower piston reducing the tendency to get into detonation on the sharper edges of valve pockets, or edges of pistons The coatings tend to keep the to heat locked into the combustion chamber where it promotes a more rapid flame front, reducing the need for longer ignition advance curves.that reduction in heat tends to reduce the reduction in strength that high engine temperatures can have on aluminum alloys, that tends to increase piston life and durability.
you can run a little tighter than before since your pistons will stay cooler and not expand as much, that means less rocking when cold and a tighter bore fit for better oil control and better ring seal.
most shops carefully tape the ring grooves then chemically etch the piston decks to gain a better mechanical grip to the pistons upper surface for the thermal barrier coating, some shops use a steel shot process, to gain a micro rough surface finish before the coating applied.
while the price to coat a piston can easily come to 50% of the cost of the less expensive pistons if it prevents a catastrophic engine failure its well worth the expense
while thermal coating benefit's either the piston or the combustion chamber ,yet it tends to do more, if on the piston,too increase piston durability through reducing heat that tends to reduce aluminum strength in the piston deck or top surface area,
and coating the combustion chamber probably results in a bit more efficient burn in the combustion chamber , as more heat energy is at least for a few fractions of a second retained in the expanding combustion gases,and marginally less heat transfer to the heads, valves and coolant can occur, so in theory you get a bit longer pressure pulse above the piston with either option, but with the combustion chamber coating I think you'll benefit the power/tq curve just marginally more, but that piston durability factors probably more critical to longer term engine durability
links with more detailed info,
http://www.thermaltechcoatings.com/services.htm
http://www.hightechcoatings.com
viewtopic.php?f=53&t=4516
http://www.circletrack.com/enginetech/c ... index.html
http://www.circletrack.com/enginetech/c ... tions.html
http://www.swaintech.com/store.asp?pid=10971
http://www.swaintech.com/store.asp?pid=10539
http://www.performancecoatings.com/enginecoatings.html
http://www.powdercoatingmn.com/power.html
http://www.calicocoatings.com/
engine Coatings - Coated Paths to Power
Race Engine Coatings
These lifters feature a special...
Race Engine Coatings
These lifters feature a special DLC coating. DLC stands for diamond like carbon which creates a super low friction surface that is both harder and more scratch resistant than conventional surfaces. Courtesy of Comp Cams
Dry Film Lubricants - These are the friction reducers, sometimes called "solid film lubricants." Far surpassing the benefits of bygone molybdenum disulfide suspended in lubrication oil, dry film lubricants are highly effective in reducing friction, heat, and surface galling. Since the lubricity portions of these materials are what provide the benefits, it's important that a good binder be utilized to keep the lubricants in place. Aside from gains made in friction reduction (particularly friction horsepower), the companion benefit is in heat reduction at the working surfaces.
Chemical or Corrosion Resistant Coatings - Materials in this category serve two fundamental purposes; (1) extended product durability or use life and (2) maintenance of appearance. We'll touch on specific areas where these coatings are of value a bit later.
In the same order they were previously presented, let's examine some specific uses for the coatings categories discussed.
Thermal Barriers - Here, the obvious areas are the combustion space and exhaust gas path. As mentioned earlier, my first and disappointing experience coating piston crowns showed power gains but damaged parts. Fortunately, with today's coatings technology, such problems are passe. So as you might expect, coating piston tops (and bottoms), combustion chambers (in certain applications), the faces of intake and exhaust valves, and complete header systems with these type of heat-retention coatings can be of particular benefit. Keep in mind that power equates with heat in a controlled environment. Therefore, combustion heat lost to cooling systems, combustion surfaces (all of them), and along the exhaust path can combine to reduce net power. Your best bet is to either consult with your choice of parts manufacturer already providing coated parts, or identify a good supplier of coatings materials if you elect to do the job yourself. And don't rule out the latter. Given the current state of some "kits" that are user-friendly to the engine builder, you can also get good results by these methods.
Race Engine Coatings
This camshaft has a new pro...
Race Engine Coatings
This camshaft has a new pro plasma nitriding process that enhances the performance all around. Courtesy of Comp Cams
Thermal Dispersants - Wherever you find that heat buildup is a concern, these are the materials to consider. Such components as brake parts, oil pans, radiators and intake manifolds all can fall into the need for rapid heat transfer or control. In areas where continual and/or repeated temperature spikes occur and you need to move heat more quickly away from these locations, consider these coatings to be of value.
Dry Film Lubricants - Remember, simply stated, friction horsepower is the arithmetic difference between indicated horsepower and brake horsepower. Therefore, the lower the friction horsepower, the higher the brake horsepower. So, by the use of dry film lubricants in areas that will net a reduction in friction horsepower, you can expect net power gained at the flywheel. Also expect a reduction in both surface and component operating temperatures. Applicable parts include valve springs, engine bearings, camshafts, and piston skirts and pins. Once again, you have the options of either selecting precoated parts or consulting with one of the coatings providers. Should you decide on the first option, it's wise to spend time talking with the manufacturer about the material (and its benefits) on any precoated component.
In this section, it may be helpful to discuss the benefits from coating certain major engine components. We'll include a few reasons and their basis, too. Our intention here is to stimulate some thoughts to the extent you'll begin to identify other parts and how they may benefit from coatings that address specific problems.
Valve Springs - Smokey once contended that valve springs raise the operating temperature of engine oil more than combustion heat. He'd already discovered that with his own version of today's "Spintron" spin fixture. Included in that discussion was his belief, other than valve float, that heat foreshortens spring life more than anything else.
Essentially, there are two sources of heat in a valve spring. One is derived from the friction of a spring moving against other surfaces (inner springs, harmonic dampers, etc.) and the other from the "flexing" or "working" of spring material during normal operation. Studies have shown that a valve spring is never motionless, even when the valve is seated. Residual energy and harmonics traverse an otherwise "static" spring, while the valve is on its seat. Consequently, heat within spring material is continually being generated. Heat is a principle source of damage to springs and, since valve springs are cooled by oil, you can expect other parts of the engine to correspondingly experience increased oil temperature.
most shops that, customize pistons round off any sharp edges, cut the piston valve clearance, notches and polish the pistons to reduce heat absorption and reduce detonation, and some coat the pistons coat the top surface with a thermal barrier coating, some match it with a combustion chamber thermal barrier coating , the coating your showing is designed to hold oil and reduce friction
you might want to read thru these threads and their sub links
viewtopic.php?f=53&t=2610&p=6737&hilit=coating+thermal#p6737
viewtopic.php?f=50&t=501&p=11829&hilit=clay+clearance#p11829
viewtopic.php?f=53&t=4472&p=11747&hilit=domes#p11747
THERMAL BARRIER DESIGNED TO REDUCE HEAT TRANSFER< AND INCREASE POWER
oil shedding coating on the under surface of the piston designed to speed heat transfer and reduce oil retention to reduce weight
outer skirt coating designed to increase wear resistance and retain oil film
Last edited by a moderator:
